12-16-2010, 10:29 AM
I had a septic repair where a new 20' run was put in with less than 3" drop over the whole run - passed all inspections, didn't give trouble the year before we sold.
The problem we had there was when groundwater rose above the drainfield level, shower drains were less than 6" above outside ground level - previous owners had brought in fill over the whole back yard - too much fill. Still, it was only a problem during sustained torrential rains of 3 days or more.